explicitly reject empty names in dynamic linker load_library function

[musl] / src / process / posix_spawn.c

diff --git a/src/process/posix_spawn.c b/src/process/posix_spawn.c
index e6a031c..ae262f7 100644 (file)
--- a/src/process/posix_spawn.c
+++ b/src/process/posix_spawn.c
@@ -20,38 +20,66 @@ struct args {
        char *const *argv, *const *envp;
 };
 
+void __get_handler_set(sigset_t *);
+
+static int __sys_dup2(int old, int new)
+{
+#ifdef SYS_dup2
+       return __syscall(SYS_dup2, old, new);
+#else
+       if (old==new) {
+               int r = __syscall(SYS_fcntl, old, F_GETFD);
+               return r<0 ? r : old;
+       } else {
+               return __syscall(SYS_dup3, old, new, 0);
+       }
+#endif
+}
+
 static int child(void *args_vp)
 {
        int i, ret;
-       struct sigaction sa;
+       struct sigaction sa = {0};
        struct args *args = args_vp;
        int p = args->p[1];
        const posix_spawn_file_actions_t *fa = args->fa;
        const posix_spawnattr_t *restrict attr = args->attr;
+       sigset_t hset;
 
        close(args->p[0]);
 
        /* All signal dispositions must be either SIG_DFL or SIG_IGN
         * before signals are unblocked. Otherwise a signal handler
         * from the parent might get run in the child while sharing
-        * memory, with unpredictable and dangerous results. */
+        * memory, with unpredictable and dangerous results. To
+        * reduce overhead, sigaction has tracked for us which signals
+        * potentially have a signal handler. */
+       __get_handler_set(&hset);
        for (i=1; i<_NSIG; i++) {
-               __libc_sigaction(i, 0, &sa);
-               if (sa.sa_handler!=SIG_DFL && (sa.sa_handler!=SIG_IGN ||
-                   ((attr->__flags & POSIX_SPAWN_SETSIGDEF)
-                    && sigismember(&attr->__def, i) ))) {
+               if ((attr->__flags & POSIX_SPAWN_SETSIGDEF)
+                    && sigismember(&attr->__def, i)) {
                        sa.sa_handler = SIG_DFL;
-                       __libc_sigaction(i, &sa, 0);
+               } else if (sigismember(&hset, i)) {
+                       if (i-32<3U) {
+                               sa.sa_handler = SIG_IGN;
+                       } else {
+                               __libc_sigaction(i, 0, &sa);
+                               if (sa.sa_handler==SIG_IGN) continue;
+                               sa.sa_handler = SIG_DFL;
+                       }
+               } else {
+                       continue;
                }
+               __libc_sigaction(i, &sa, 0);
        }
 
        if (attr->__flags & POSIX_SPAWN_SETPGROUP)
                if ((ret=__syscall(SYS_setpgid, 0, attr->__pgrp)))
                        goto fail;
 
-       /* Use syscalls directly because pthread state because the
-        * library functions attempt to do a multi-threaded synchronized
-        * id-change, which would trash the parent's state. */
+       /* Use syscalls directly because the library functions attempt
+        * to do a multi-threaded synchronized id-change, which would
+        * trash the parent's state. */
        if (attr->__flags & POSIX_SPAWN_RESETIDS)
                if ((ret=__syscall(SYS_setgid, __syscall(SYS_getgid))) ||
                    (ret=__syscall(SYS_setuid, __syscall(SYS_getuid))) )
@@ -78,15 +106,14 @@ static int child(void *args_vp)
                                        goto fail;
                                break;
                        case FDOP_DUP2:
-                               if ((ret=__syscall(SYS_dup2, op->srcfd, op->fd))<0)
+                               if ((ret=__sys_dup2(op->srcfd, op->fd))<0)
                                        goto fail;
                                break;
                        case FDOP_OPEN:
-                               fd = __syscall(SYS_open, op->path,
-                                       op->oflag | O_LARGEFILE, op->mode);
+                               fd = __sys_open(op->path, op->oflag, op->mode);
                                if ((ret=fd) < 0) goto fail;
                                if (fd != op->fd) {
-                                       if ((ret=__syscall(SYS_dup2, fd, op->fd))<0)
+                                       if ((ret=__sys_dup2(fd, op->fd))<0)
                                                goto fail;
                                        __syscall(SYS_close, fd);
                                }
@@ -105,6 +132,7 @@ static int child(void *args_vp)
                ? &attr->__mask : &args->oldmask, 0);
 
        args->exec(args->path, args->argv, args->envp);
+       ret = -errno;
 
 fail:
        /* Since sizeof errno < PIPE_BUF, the write is atomic. */
@@ -138,7 +166,8 @@ int __posix_spawnx(pid_t *restrict res, const char *restrict path,
        args.envp = envp;
        pthread_sigmask(SIG_BLOCK, SIGALL_SET, &args.oldmask);
 
-       pid = __clone(child, stack+sizeof stack, CLONE_VM|SIGCHLD, &args);
+       pid = __clone(child, stack+sizeof stack,
+               CLONE_VM|CLONE_VFORK|SIGCHLD, &args);
        close(args.p[1]);
 
        if (pid > 0) {
@@ -150,7 +179,7 @@ int __posix_spawnx(pid_t *restrict res, const char *restrict path,
 
        close(args.p[0]);
 
-       if (!ec) *res = pid;
+       if (!ec && res) *res = pid;
 
        pthread_sigmask(SIG_SETMASK, &args.oldmask, 0);
        pthread_setcancelstate(cs, 0);